1. Field of the Invention
This invention relates to a novel process for preparing bisphenol sulfone derivatives.
2. Description of the Prior Art
Generally, the oxidation of sulfur compounds is effected in a glacial acetic acid solution by using solely hydrogen peroxide as oxidizing agent (peracetic acid oxidation).
The following have been known about the process in which bisphenol sulfides or bisphenol sulfoxides are oxidized to obtain the corresponding sulfones.
(1) The oxidation of sulfides with hydrogen peroxide is usually effected in glacial acetic acid (peracetic acid oxidation), but it also proceeds in an organic solvent such as acetone.
(2) The oxidation of 2,2'-bisphenol sulfides with hydrogen peroxide is effected in a similar way as above in glacial acetic acid to obtain the corresponding 2,2'-bisphenol sulfone derivatives [J. Am. Chem. Soc., 67. 238 (1945)].
(3) In a conventional process, 4,4'-diphenol sulfide is oxidized in the presence of a metallic catalyst such as molybdenum, vanadium, titanium, tungsten, or the like, in an aqueous acid solution to obtain 4,4'-diphenol sulfone. 4,4'-Diphenol sulfide is subjected to heating under reflux with a pH not more than 1 in the presence of molybdenum to obtain the final product at an yield of 99.7% (purity 97.6%) (U.S. Pat. No. 4,089,904).
(4) In the case of the preparation of bisphenol sulfone by the oxidation of bisphenol sulfoxide, the 4,4'-bisphenol sulfoxide is oxidized with hydrogen peroxide in glacial acetic acid to obtain the corresponding sulfone. For example, 4,4'-diphenol sulfoxide is subjected to oxidation at 85.degree. C. in a large excess of glacial acetic acid to obtain the final product at a yield of 85% [L. M. Nikolenko et al, J. General Chem. of USSR, 33, 3664 (1963)].
(5) Nothing is known about the oxidation reaction of 2,2'-bisphenol sulfoxides. 2,2'-Bisphenol sulfoxides are only expected to form the corresponding 2,2'-bisphenol sulfone derivatives by the peracetic acid oxidation as in 4,4'-bisphenol sulfoxide mentioned above.
However, such processes as mentioned in the above items (2), (4) and (5) have many drawbacks from the standpoints of economy as well as procedures for the preparation thereof in effecting these reactions on an industrial scale, because the oxidation reaction is effected in a large excess of peracetic acid, so that the handling thereof requires to take bumpings and explosions into consideration, and because a large amount of glacial acetic acid is used and discharged into a large amount of waste water, which requires a large amount of expenditure including that for the waste liquor disposal and so forth.
The process described in the above item (3) cannot be regarded as economical and advantageous for industrial purposes due to the following reasons. In the process, a relatively expensive metallic catalyst is used, and the recovery thereof requires complicated procedures and many problems associated with environmental protections take place, because the catalyst is dissolved in the aqueous solution. Moreover, the process has such problems that the reaction conditions especially of pH remarkably affect the yield and purity of the final product, that the product is colored, and so forth.